All Calculators

Popular Calculators

Frequently used tools from across the library — a good place to start.

Math & Percentage

• Percent Change CalculatorCalculate the percentage change between two values.
• Percentage CalculatorFree multi-mode percentage calculator: percent of a number, what percent X is of Y, reverse percentage, percentage change, increase/decrease by a percent, decimal ↔ percent, and fraction → percent.
• Percentage Increase CalculatorFree percentage increase calculator: find the percent growth from an old value to a new higher value, or the new value after a given increase.
• Percentage Decrease CalculatorFree percentage decrease calculator: find the percent drop from an old value to a new lower value, or the value after a given decrease.
• Discount CalculatorFree discount calculator: find the sale price and dollar savings from a percent-off deal, and see how stacked discounts really combine.
• Sales Tax CalculatorFree sales tax calculator: add any sales tax rate to a price to get the tax amount and total, or reverse-calculate the pre-tax price from a total.
• Tip CalculatorFree tip calculator: work out the tip amount, the total bill, and each person's share when splitting.

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Salary & Paycheck

• Salary & Pay ConverterConvert pay between hourly, daily, weekly, bi-weekly, semi-monthly, monthly, and annual — in any direction.
• Take-Home Pay CalculatorSee what your salary actually deposits after taxes and deductions.
• Overtime Pay CalculatorCalculate your total weekly gross pay including overtime.

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Money, Loans & Mortgage

• Loan Payment CalculatorCalculate the monthly payment on a fixed-rate loan.
• Mortgage CalculatorEstimate your monthly mortgage payment from home price, down payment, interest rate, and term.
• Credit Card Payoff CalculatorSee exactly how many months it takes to pay off your credit card balance — and how much interest you pay — with fixed monthly payments.
• Simple Interest CalculatorCalculate simple interest and total amount from principal, rate, and time.
• Compound Interest CalculatorCalculate how an investment or savings balance grows with compound interest.

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Time & Work

• Time Duration CalculatorCalculate elapsed time between a start and end time, with next-day handling.
• Work Hours CalculatorCalculate net work hours from clock-in and clock-out times, with an optional break deduction.
• Gas Cost Increase CalculatorFind out exactly what a gas price change costs you monthly and yearly based on your real driving.

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Conversions

• Temperature ConverterFree temperature converter between Celsius, Fahrenheit, and Kelvin.
• Weight & Mass ConverterFree weight and mass converter between kilograms, pounds, grams, ounces, milligrams, metric tons, and US tons.
• Length & Distance ConverterFree length and distance converter between miles, kilometers, meters, feet, inches, yards, centimeters, and millimeters.

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Business

• Cash Runway CalculatorEnter cash on hand, average monthly cash in, and cash out — see your monthly burn and how many months your business can operate before the account hits zero.
• Break-Even Revenue CalculatorEnter monthly fixed costs and gross margin — get the monthly and per-day revenue your business must produce before it earns its first dollar of profit.
• Overhead Recovery CalculatorEnter annual overhead and billable hours — see the overhead each billable hour must recover, and what share of revenue your overhead consumes.
• Customer Acquisition Payback CalculatorEnter monthly marketing spend, new customers won, and gross profit per customer per month — get your CAC and how many months until a customer repays it.
• Price Increase Impact CalculatorModel a price increase: enter revenue, gross margin, increase percentage, and expected customer loss — see the profit change and how many customers you can afford to lose.
• Freelance Rate BuilderWork backward from the income you need: enter target income, overhead, billable hours, and a buffer — get the hourly rate your freelance business must charge.

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Construction & Trades

• Labor Burden CalculatorThe wage is not the cost.
• Crew Cost CalculatorEnter crew size, burdened hourly cost, hours per day, and days on the job — get the real cost of putting your crew on site, per hour, per day, and for the whole job.
• Break-Even Job Price CalculatorEnter direct job costs, overhead percentage, and target margin — get the price where the job stops losing money and the price that actually hits your profit target.
• Bid Check CalculatorStress-test a bid before you send it.
• Job Profit Margin CalculatorEnter contract price, labor, materials, subs, and overhead share — see the job's gross profit, gross margin, and true margin after overhead.
• Callback Cost CalculatorCallbacks are unbilled jobs.
• Missed Lead Value CalculatorEnter missed leads per month, close rate, average job revenue, and margin — see the revenue and gross profit walking past your business every year.

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Methodology & Trust

How these calculators are built, who reviews them, and the limits of the estimates.

• MethodologyThe house method: formula shown, assumptions stated, worked examples, and limitations on every serious tool.
• About CalcAuthorityWho builds and reviews the calculators, and the standards behind them.
• Financial DisclaimerResults are educational estimates for planning — not financial, tax, legal, or accounting advice.